Define the term background radiation.
State one natural source and one artificial source of background radiation.
Radon-222 (86222Rn^{222}_{86}\text{Rn}86222Rn) is a radioactive gas. It decays by emitting an alpha (α\alphaα) particle to form an isotope of polonium (Po\text{Po}Po).
Complete the nuclide equation for this decay:
86222Rn⟶………Po+………α ^{222}_{86}\text{Rn} \longrightarrow \dots^{\dots}_{\dots}\text{Po} + \dots^{\dots}_{\dots}\alpha 86222Rn⟶………Po+………αIf an alpha emitter is used for cancer treatment, it must be delivered directly into the tumor. Explain why an external alpha source would not be effective for treating internal tumors.
Technetium-99m is a common medical tracer injected into patients to produce images of internal organs. It has a half-life of 6 hours and decays by emitting gamma (γ\gammaγ) radiation.
Explain why a gamma emitter is used rather than an alpha emitter for this type of medical imaging.
Explain why it is important for the tracer to have a short half-life.
484 exam-style questions on CIE IGCSE Physics 5.2 Radioactivity, covering 5.2.1 Background radiation and measuring count rate, 5.2.2a Alpha, beta and gamma emission, 5.2.2b Deflection and ionising effects of nuclear radiation, 5.2.3a Radioactive decay, 5.2.3b Effects of decay on the nucleus and decay equations, 5.2.4a Half-life, 5.2.4b Choosing isotopes for applications, and 5.2.5 Effects of ionising radiation and safety precautions. Each one has a worked solution and a mark scheme showing where the marks go.